U.S. patent application number 13/098066 was filed with the patent office on 2012-11-01 for methods and systems for volume-targeted minimum pressure-control ventilation.
This patent application is currently assigned to Nellcor Puritan Bennett LLC. Invention is credited to Gary Milne.
Application Number | 20120272960 13/098066 |
Document ID | / |
Family ID | 47066936 |
Filed Date | 2012-11-01 |
United States Patent
Application |
20120272960 |
Kind Code |
A1 |
Milne; Gary |
November 1, 2012 |
Methods and Systems for Volume-Targeted Minimum Pressure-Control
Ventilation
Abstract
This disclosure describes systems and methods for providing a
volume-targeted minimum pressure-control breath type during
ventilation of a patient. The disclosure describes a novel breath
type that allows an operator to input a tidal volume and receive
some of the benefits of utilizing an airway pressure release
ventilation (APRV) breath type in combination with some of the
benefits of utilizing a volume-targeted-pressure-control (VC+)
breath type.
Inventors: |
Milne; Gary; (Louisville,
CO) |
Assignee: |
Nellcor Puritan Bennett LLC
Boulder
CO
|
Family ID: |
47066936 |
Appl. No.: |
13/098066 |
Filed: |
April 29, 2011 |
Current U.S.
Class: |
128/204.23 |
Current CPC
Class: |
A61M 2205/18 20130101;
A61M 16/0833 20140204; A61M 16/024 20170801; A61M 16/00 20130101;
A61M 2205/505 20130101; A61M 16/0063 20140204; A61M 16/12 20130101;
A61M 16/0051 20130101; A61M 2016/0036 20130101 |
Class at
Publication: |
128/204.23 |
International
Class: |
A61M 16/00 20060101
A61M016/00 |
Claims
1. A method for ventilating a patient with a ventilator comprising:
receiving a tidal volume and a PEEP; receiving a minimum
inspiration pressure; receiving at least two of an inspiration
time, an exhalation time, an I:E ratio, and a respiratory rate;
calculating a calculated pressure based on measurements taken from
a previous inspiration indicative of tidal volume delivered to the
patient; comparing the calculated pressure to the received minimum
inspiration pressure; delivering a delivered inspiration pressure
during a next inhalation to the patient, the delivered inspiration
pressure determined based on the step of comparing the calculated
pressure to the received minimum inspiration pressure; and
delivering, after the next inhalation, the received PEEP.
2. The method of claim 1, wherein the step of comparing the
calculated pressure to the received minimum inspiration pressure
includes determining that the calculated pressure is less than the
received minimum inspiration pressure, and wherein the step of
delivering the inspiration pressure during inhalation to the
patient includes delivering the received minimum inspiration
pressure during inhalation to the patient.
3. The method of claim 1, wherein the step of comparing the
calculated pressure to the received minimum inspiration pressure
includes determining that the calculated pressure is more than the
received minimum inspiration pressure, and wherein the step of
delivering the inspiration pressure during inhalation to the
patient includes delivering the calculated pressure during
inhalation to the patient.
4. The method of claim 1, wherein the I:E ratio is greater than
4:1.
5. The method of claim 1, further comprising receiving at least one
of a rise time and a FiO.sub.2.
6. The method of claim 1, further comprising: delivering a
spontaneous breath in response to a patient initiated trigger
during inspiration and expiration above the delivered inspiration
pressure and the delivered PEEP.
7. The method of claim 6, further comprising receiving a pressure
support setting that is applied to the delivered spontaneous
breath.
8. The method of claim 6, further comprising tracking the delivered
spontaneous breath.
9. The method of claim 1, further comprising: receiving an
inspiration pressure maximum; and comparing the inspiration
pressure maximum to the calculated pressure.
10. The method of claim 9, wherein the step of comparing the
calculated pressure to the maximum inspiration pressure includes
determining that the calculated pressure is less than the maximum
inspiration pressure, and wherein the step of delivering the
inspiration pressure during inhalation to the patient includes
delivering the calculated pressure during inhalation to the
patient.
11. The method of claim 9, further comprising: wherein the step of
comparing the calculated pressure to the maximum inspiration
pressure includes determining that the calculated pressure is more
than the maximum inspiration pressure, and wherein the step of
delivering the inspiration pressure during inhalation to the
patient includes delivering the maximum inspiration pressure during
inhalation to the patient.
12. The method of claim 9, wherein the maximum inspiration pressure
is calculated based on the minimum inspiration pressure.
13. The method of claim 9, further comprising: receiving the
minimum inspiration pressure from a default minimum inspiration
pressure setting in the ventilator; and receiving the maximum
inspiration pressure from a default maximum inspiration setting in
the ventilator.
14. The method of claim 1, further comprising: receiving the
received minimum inspiration pressure from a default minimum
inspiration pressure setting in the ventilator.
15. The method of claim 1, further comprising: receiving the
received PEEP from a default PEEP setting in the ventilator.
16. The method of claim 1, further comprising: executing an alarm
when the received tidal volume is not delivered to the patient; and
executing an alarm when the inspired volume of the patient is above
a predetermined threshold.
17. A ventilator system comprising: a pressure generating system
adapted to generate a flow of breathing gas; a ventilation tubing
system including a patient interface for connecting the pressure
generating system to a patient; one or more sensors operatively
coupled to at least one of the pressure generating system, the
patient, and the ventilation tubing system, wherein at least one
sensor is capable of generating an output indicative of an
inspiration flow; and a VCI module that calculates an inspiration
pressure based on a received tidal volume from the output
indicative of the inspiration flow and causes the pressure
generating system to deliver at least one of a calculated pressure
or a received minimum pressure to the patient during
inhalation.
18. A computer-readable medium having computer-executable
instructions for performing a method of ventilating a patient with
a ventilator, the method comprising: repeatedly receiving a tidal
volume and a PEEP; repeatedly receiving a minimum inspiration
pressure; repeatedly receiving at least two of an inspiration time,
an exhalation time, an I:E ratio, and a respiratory rate;
repeatedly calculating a calculated pressure based on measurements
taken from a previous inspiration indicative of tidal volume
delivered to the patient; repeatedly comparing the calculated
pressure to the received minimum inspiration pressure; repeatedly
delivering a delivered inspiration pressure during a next
inhalation to the patient, the delivered inspiration pressure
determined based on the step of comparing the calculated pressure
to the received minimum inspiration pressure; and repeatedly
delivering, after the next inhalation, the received PEEP.
19. A ventilator system, comprising: means for receiving a tidal
volume and a PEEP; means for receiving a minimum inspiration
pressure; means for receiving at least two of an inspiration time,
an exhalation time, an I:E ratio, and a respiratory rate; means for
calculating a calculated pressure based on measurements taken from
a previous inspiration indicative of tidal volume delivered to the
patient; means for comparing the calculated pressure to the
received minimum inspiration pressure; means for delivering a
delivered inspiration pressure during a next inhalation to the
patient, the delivered inspiration pressure determined based on the
step of comparing the calculated pressure to the received minimum
inspiration pressure; and means for delivering, after the next
inhalation, the received PEEP.
Description
INTRODUCTION
[0001] Medical ventilator systems have long been used to provide
ventilatory and supplemental oxygen support to patients. These
ventilators typically comprise a source of pressurized oxygen which
is fluidly connected to the patient through a conduit or tubing. As
each patient may require a different ventilation strategy, modern
ventilators can be customized for the particular needs of an
individual patient. For example, several different ventilator modes
have been created to provide better ventilation for patients in
various different scenarios.
Volume-Targeted Minimum Pressure-Control Ventilation
[0002] This disclosure describes systems and methods for providing
a volume-targeted minimum pressure-control breath type during
ventilation of a patient. The disclosure describes a novel breath
type that allows an operator to input a tidal volume and receive
some of the benefits of utilizing an airway pressure release
ventilation (APRV) breath type in combination with some of the
benefits of utilizing a volume-targeted-pressure-control (VC+)
breath type.
[0003] In part, this disclosure describes a method for ventilating
a patient with a ventilator. The method includes:
[0004] a) receiving a tidal volume and a PEEP;
[0005] b) receiving a minimum inspiration pressure;
[0006] c) receiving at least two of an inspiration time, an
exhalation time, an I:E ratio, and a respiratory rate;
[0007] d) calculating a calculated pressure based on measurements
taken from a previous inspiration indicative of tidal volume
delivered to the patient;
[0008] e) comparing the calculated pressure to the received minimum
inspiration pressure;
[0009] delivering a delivered inspiration pressure during a next
inhalation to the patient, the delivered inspiration pressure
determined based on the step of comparing the calculated pressure
to the received minimum inspiration pressure; and
[0010] f) delivering, after the next inhalation, the received
PEEP.
[0011] Yet another aspect of this disclosure describes a ventilator
system that includes: a pressure generating system adapted to
generate a flow of breathing gas; a ventilation tubing system
including a patient interface for connecting the pressure
generating system to a patient; one or more sensors operatively
coupled to at least one of the pressure generating system, the
patient, and the ventilation tubing system, wherein at least one
sensor is capable of generating an output indicative of an
inspiration flow; and a VCI module that calculates an inspiration
pressure based on a received tidal volume from the output
indicative of the inspiration flow and causes the pressure
generating system to deliver at least one of a calculated pressure
or a received minimum pressure to the patient during
inhalation.
[0012] The disclosure further describes a computer-readable medium
having computer-executable instructions for performing a method for
ventilating a patient with a ventilator. The method includes:
[0013] a) repeatedly receiving a tidal volume and a PEEP;
[0014] b) repeatedly receiving a minimum inspiration pressure;
[0015] c) repeatedly receiving at least two of an inspiration time,
an exhalation time, an I:E ratio, and a respiratory rate;
[0016] d) repeatedly calculating a calculated pressure based on
measurements taken from a previous inspiration indicative of tidal
volume delivered to the patient;
[0017] e) repeatedly comparing the calculated pressure to the
received minimum inspiration pressure;
[0018] f) repeatedly delivering a delivered inspiration pressure
during a next inhalation to the patient, the delivered inspiration
pressure determined based on the step of comparing the calculated
pressure to the received minimum inspiration pressure; and
[0019] g) repeatedly delivering, after the next inhalation, the
received PEEP.
[0020] The disclosure also describes a ventilator system including
means for means for receiving a tidal volume and a PEEP; means for
receiving a minimum inspiration pressure;
[0021] means for receiving at least two of an inspiration time, an
exhalation time, an I:E ratio, and a respiratory rate; means for
calculating a calculated pressure based on measurements taken from
a previous inspiration indicative of tidal volume delivered to the
patient; means for comparing the calculated pressure to the
received minimum inspiration pressure; means for delivering a
delivered inspiration pressure during a next inhalation to the
patient, the delivered inspiration pressure determined based on the
step of comparing the calculated pressure to the received minimum
inspiration pressure; and means for delivering, after the next
inhalation, the received PEEP.
[0022] These and various other features as well as advantages which
characterize the systems and methods described herein will be
apparent from a reading of the following detailed description and a
review of the associated drawings. Additional features are set
forth in the description which follows, and in part will be
apparent from the description, or may be learned by practice of the
technology. The benefits and features of the technology will be
realized and attained by the structure particularly pointed out in
the written description and claims hereof as well as the appended
drawings.
[0023] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory and are intended to provide further explanation of
the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The following drawing figures, which form a part of this
application, are illustrative of embodiments of systems and methods
described below and are not meant to limit the scope of the
invention in any manner, which scope shall be based on the claims
appended hereto.
[0025] FIG. 1 illustrates an embodiment of a ventilator.
[0026] FIG. 2 illustrates an embodiment of a method for ventilating
a patient on a ventilator with a VCI breath type.
[0027] FIG. 3 illustrates an embodiment of a pressure waveform
showing changes from inspiration to expiration during a VIC breath
type.
DETAILED DESCRIPTION
[0028] Although the techniques introduced above and discussed in
detail below may be implemented for a variety of medical devices,
the present disclosure will discuss the implementation of these
techniques in the context of a medical ventilator for use in
providing ventilation support to a human patient. The reader will
understand that the technology described in the context of a
medical ventilator for human patients could be adapted for use with
other systems such as ventilators for non-human patients and
general gas transport systems.
[0029] Medical ventilators are used to provide a breathing gas to a
patient who may otherwise be unable to breathe sufficiently. In
modern medical facilities, pressurized air and oxygen sources are
often available from wall outlets. Accordingly, ventilators may
provide pressure regulating valves (or regulators) connected to
centralized sources of pressurized air and pressurized oxygen. The
regulating valves function to regulate flow so that respiratory gas
having a desired concentration of oxygen is supplied to the patient
at desired pressures and rates. Ventilators capable of operating
independently of external sources of pressurized air are also
available.
[0030] While operating a ventilator, it is desirable to control the
percentage of oxygen in the gas supplied by the ventilator to the
patient. Further, as each patient may require a different
ventilation strategy, modern ventilators can be customized for the
particular needs of an individual patient. For example, several
different ventilator breath types have been created to provide
better ventilation for patients in various different scenarios.
[0031] Volume ventilation refers to various forms of
volume-targeted ventilation that utilize a clinician set tidal
volume to regulate some aspect of the delivery of gas (e.g.,
inhalation pressure, inhalation duration, cycling criteria, etc.)
to the patient. Different types of volume ventilation are available
depending on the specific implementation of volume regulation. For
example, for volume-cycled ventilation, an end of inspiration is
determined based on monitoring the volume delivered to the patient.
Volume ventilation may include volume-control (VC) breath type.
Another form of volume ventilation is that in which the pressure
delivered during inhalation is some function of a clinician-set
tidal volume target. Volume-targeted-pressure-control (VC+), or
volume-support (VS) breath types are examples of this type of
volume ventilation.
[0032] A landmark study published by The New England Journal of
Medicine was conducted in the year 2000 that utilized
volume-control ventilation on airway respiratory distress syndrome
(ARDS) patients..sup.1 ARDS is caused by a variety of different
direct and indirect issues, which impairs gas exchange in the
lungs. This study found a significant reduction in mortality when
4-6 ml/kg of tidal volume in VC ventilation was utilized on ARDS
patients. This study is the most widely accepted study in the
United States and still drives the use of VC ventilation today.
Accordingly, most clinicians are familiar with VC ventilation and
its settings. However, VC ventilation is a mandatory mode that is
often found to be very uncomfortable by patients. Many patients
fight the mandatory settings of this mode requiring them to be
sedated. Sedation of patients has been shown to increase costs by
$66,000..sup.2 .sup.1Roy G. Brower, M. D. et al., Ventilation with
Lower Tidal Volumes as Compared with Traditional Tidal Volumes for
Acute Lung Injury and the Acute Respiratory Distress Syndrome,
342(18) NEW ENG. J. MED. 1301, 1301-08 (2000)..sup.2Maria I. Rudis,
PharmD, BCPS et al., Economic Impact of Prolonged Motor Weakness
Complicating Neuromuscular Blockade in the Intensive Care Unit,
24(10) CRITICAL CARE MED. 1749, 1749-1756 (1996).
[0033] Pressure-targeted breath types may be provided by regulating
the pressure delivered to the patient in various ways. For example,
during pressure-cycled ventilation, an end of inspiration is
determined based on monitoring the pressure delivered to the
patient. Pressure ventilation may include a pressure-support (PS),
a proportional assist (PA), or a pressure-control (PC) breath type,
for example. Pressure ventilation may also include various forms of
BiLevel.TM. (BL) ventilation, i.e., pressure ventilation in which
the inhalation positive airway pressure (IPAP) is higher than the
exhalation positive airway pressure (EPAP).
[0034] The different breath types may also be provided as part of a
BiLevel.TM. (BL) mode of ventilation. In BL mode the ventilator
delivers breaths (either spontaneous or controlled breaths) while
cycling between two exhalation pressure levels over time so that
all breaths being delivered during a first period will use a first
low exhalation pressure (PEEP.sub.L) and all breaths delivered
during the second period will use a second, higher, exhalation
pressure (PEEP.sub.H). The transition between PEEP.sub.L and
PEEP.sub.H may be synchronized to a patient's spontaneous breathing
efforts and/or to the ventilator-controlled breaths.
[0035] BL mode ventilation is one approach being utilized today to
treat ARDS patients in an attempt to decrease sedation. In order to
treat ARDS patients, the BLmode is set with an inspiration to
expiration (I:E) ratio inverse enough to become similar to airway
pressure release ventilation (APRV) (e.g., I:E ratio of 5:1). This
current strategy is also being promoted by the American Association
for Respiratory Care as a ventilation strategy for H1N1
patients.
[0036] Clinicians are increasing the use of BL mode ventilation.
However, BL mode requires setting a PEEP.sub.H and PEEP.sub.L,
which are very different from the tidal volume setting of the more
commonly utilized volume control breath types. Accordingly, several
clinicians are hesitant to utilize BL mode ventilation, since they
would have to learn an entirely new system for setting, managing,
and watching this type of ventilation. Further, as lung compliance
changes in patients being ventilated in BL mode, volume can exceed
desired levels.
[0037] As discussed above, the VC+ breath type is a combination of
volume and pressure control breath types that may be delivered to a
patient as a mandatory breath. In particular, VC+may provide the
benefits associated with setting a target tidal volume, while also
allowing for variable flow. Variable flow may be helpful in meeting
inhalation flow demands for actively breathing patients. In the VC+
breath type, the inspiration pressure (P) for a breath is
calculated based on the measured tidal volume of the prior breath.
When a patient spontaneously pulls under the patient's own effort a
large amount of tidal volume in a breath, the VC+ breath type
provides for less P.sub.i in the next or following breath in an
attempt to achieve the set tidal volume. Accordingly, based on the
previous breath, the patient could receive little or no assistance
in the form of inspiration pressure support during the VC+ breath
type in this situation.
[0038] Unlike VC in which tidal volume of each breath is
essentially guaranteed, when the set inhalation time is reached the
ventilator initiates exhalation in a VC+ breath type regardless of
actual tidal volume delivered in that breath. Exhalation lasts from
the end of inspiration until the beginning of the next inspiration.
For a non-triggering patient, the exhalation time (T.sub.E) is
based on the respiratory rate set by the clinician. Upon the end of
exhalation, another VC+ mandatory breath is given to the patient.
By controlling target tidal volume and allowing for variable flow,
VC+ allows a clinician to maintain the volume while allowing the
flow and pressure targets to fluctuate from breath to breath.
Providing the patient with the ability to fluctuate flow as desired
is often found by patients to be more comfortable than mandatory
volume control modes.
[0039] However, the VC+ breath type is not an ideal mode for ARDS
patients because pressure lowers in VC+ as the patient increases
their spontaneous efforts to pull more tidal volume on their own
and could result in insufficient inspiration pressure support. ARDS
patients require a minimum level of pressure support to promote gas
exchange within their lungs. Further, the VC+ breath type does not
allow for an I:E ratio of greater than 4:1, which is beneficial to
ARDS patients.
[0040] The current disclosure describes a volume targeted airway
pressure release ventilation with guaranteed minimal pressure or a
volume-targeted minimum pressure-control (VCI) breath type that
combines the benefits of VC+ with the benefits of BL and reduces
the disadvantages of each for the ventilation of patients, such as
the ventilation of weak patients with ARDS and H1N1. The VCI breath
type allows the clinician to set a tidal volume, which more
clinicians are familiar with, while still receiving the benefits of
pressure ventilation. The VCI breath type is similar to the VC+
breath type, except, the VCI breath type provides a minimum
inspiration pressure (P.sub.MIN) and allows for an inverse I:E
ratio of greater than 4:1. This inverse I:E ratio is represented in
the letter "I" of the VCI abbreviation. Further, the VCI breath
type is different from the VC+ breath type because the VCI breath
type allows the patient to spontaneously trigger inspirations above
the given P.sub.i during the inhalation period and PEEP during the
exhalation period and tracks these spontaneously triggered
inspirations. The VCI breath type may additionally provide pressure
support for detected spontaneously triggered inspirations above the
given P.sub.i and PEEP.
[0041] FIG. 1 is a diagram illustrating an embodiment of an
exemplary ventilator 100 connected to a human patient 150.
Ventilator 100 includes a pneumatic system 102 (also referred to as
a pressure generating system 102) for circulating breathing gases
to and from patient 150 via the ventilation tubing system 130,
which couples the patient 150 to the pneumatic system 102 via an
invasive (e.g., endotracheal tube, as shown) or a non-invasive
(e.g., nasal mask) patient interface 180.
[0042] Ventilation tubing system 130 (or patient circuit 130) may
be a two-limb (shown) or a one-limb circuit for carrying gases to
and from the patient 150. In a two-limb embodiment, a fitting,
typically referred to as a "wye-fitting" 170, may be provided to
couple a patient interface 180 (as shown, an endotracheal tube) to
an inhalation limb 132 and an exhalation limb 134 of the
ventilation tubing system 130.
[0043] Pneumatic system 102 may be configured in a variety of ways.
In the present example, pneumatic system 102 includes an exhalation
module 108 coupled with the exhalation limb 134 and an inhalation
module 104 coupled with the inhalation limb 132. Compressor 106 or
other source(s) of pressurized gases (e.g., air, oxygen, and/or
helium) is coupled with inhalation module 104 and the exhalation
module 108 to provide a gas source for ventilatory support via
inhalation limb 132.
[0044] The inhalation module 104 is configured to deliver gases to
the patient 150 according to prescribed ventilatory settings. In
some embodiments, inhalation module 104 is configured to provide
ventilation according to various breath types, e.g., via VC, PC,
VC+, or VCI or via any other suitable breath types.
[0045] The exhalation module 108 is configured to release gases
from the patient's lungs according to prescribed ventilatory
settings. Specifically, exhalation module 108 is associated with
and/or controls an exhalation valve for releasing gases from the
patient 150. In some embodiments, exhalation module 108 is
configured to provide exhalation according to various breath types,
e.g., via VC, PC, VC+, or VCI or via any other suitable breath
types.
[0046] The ventilator 100 may also include one or more sensors 107
communicatively coupled to ventilator 100. The sensors 107 may be
located in the pneumatic system 102, ventilation tubing system 130,
and/or on the patient 150. The embodiment of FIG. 1, illustrates a
sensor 107 in pneumatic system 102.
[0047] Sensors 107 may communicate with various components of
ventilator 100, e.g., pneumatic system 102, other sensors 107,
processor 116, volume-targeted minimal pressure-control (VCI)
module 119, and any other suitable components and/or modules. In
one embodiment, sensors 107 generate output and send this output to
pneumatic system 102, other sensors 107, processor 116, VCI module
119, and any other suitable components and/or modules. Sensors 107
may employ any suitable sensory or derivative technique for
monitoring one or more parameters associated with the ventilation
of a patient 150. Sensors 107 may detect changes in ventilatory
parameters indicative of patient triggering, for example. Sensors
107 may be placed in any suitable location, e.g., within the
ventilatory circuitry or other devices communicatively coupled to
the ventilator 100. Further, sensors 107 may be placed in any
suitable internal location, such as, within the ventilatory
circuitry or within components or modules of ventilator 100. For
example, sensors 107 may be coupled to the inhalation and/or
exhalation modules for detecting changes in, for example, circuit
pressure and/or flow. In other examples, sensors 107 may be affixed
to the ventilatory tubing or may be embedded in the tubing itself.
According to some embodiments, sensors 107 may be provided at or
near the lungs (or diaphragm) for detecting a pressure in the
lungs. Additionally or alternatively, sensors 107 may be affixed or
embedded in or near wye-fitting 170 and/or patient interface 180.
Indeed, any sensory device useful for monitoring changes in
measurable parameters during ventilatory treatment may be employed
in accordance with embodiments described herein.
[0048] The pneumatic system 102 may include a variety of other
components, including mixing modules, valves, tubing, accumulators,
filters, etc. Controller 110 is operatively coupled with pneumatic
system 102, signal measurement and acquisition systems, and an
operator interface 120 that may enable an operator to interact with
the ventilator 100 (e.g., change ventilator settings, select
operational modes, view monitored parameters, etc.).
[0049] In one embodiment the operator interface 120 of the
ventilator 100 includes a display 122 communicatively coupled to
ventilator 100. Display 122 provides various input screens, for
receiving clinician input, and various display screens, for
presenting useful information to the clinician. In one embodiment,
the display 122 is configured to include a graphical user interface
(GUI). The GUI may be an interactive display, e.g., a
touch-sensitive screen or otherwise, and may provide various
windows and elements for receiving input and interface command
operations. Alternatively, other suitable means of communication
with the ventilator 100 may be provided, for instance by a wheel,
keyboard, mouse, or other suitable interactive device. Thus,
operator interface 120 may accept commands and input through
display 122. Display 122 may also provide useful information in the
form of various ventilatory data regarding the physical condition
of a patient. The useful information may be derived by the
ventilator 100, based on data collected by a processor 116, and the
useful information may be displayed to the clinician in the form of
graphs, wave representations, pie graphs, or other suitable forms
of graphic display. For example, patient data may be displayed on
the GUI and/or display 122. Additionally or alternatively, patient
data may be communicated to a remote monitoring system coupled via
any suitable means to the ventilator 100.
[0050] Controller 110 may include memory 112, one or more
processors 116, storage 114, and/or other components of the type
commonly found in command and control computing devices. Controller
110 may further include a volume-targeted pressure-controlled (VC+)
module 117, a BiLevel.TM. (BL) module 118, and/or a volume-targeted
minimum pressure-controlled (VCI) module 119 configured to deliver
gases to the patient 150 according to a prescribed breath type as
illustrated in FIG. 1. In alternative embodiments, VC+ module 117,
the BL module 118, and VCI module 119 configured to deliver gases
to the patient 150 according to a prescribed breath type may be
located in other components of the ventilator 100, such as in the
pressure generating system 102 (also known as the pneumatic system
102).
[0051] The memory 112 includes non-transitory, computer-readable
storage media that stores software that is executed by the
processor 116 and which controls the operation of the ventilator
100. In an embodiment, the memory 112 includes one or more
solid-state storage devices such as flash memory chips. In an
alternative embodiment, the memory 112 may be mass storage
connected to the processor 116 through a mass storage controller
(not shown) and a communications bus (not shown). Although the
description of computer-readable media contained herein refers to a
solid-state storage, it should be appreciated by those skilled in
the art that computer-readable storage media can be any available
media that can be accessed by the processor 116. That is,
computer-readable storage media includes non-transitory, volatile
and non-volatile, removable and non-removable media implemented in
any method or technology for storage of information such as
computer-readable instructions, data structures, program modules or
other data. For example, computer-readable storage media includes
RAM, ROM, EPROM, EEPROM, flash memory or other solid state memory
technology, CD-ROM, DVD, or other optical storage, magnetic
cassettes, magnetic tape, magnetic disk storage or other magnetic
storage devices, or any other medium which can be used to store the
desired information and which can be accessed by the computer.
[0052] In some embodiments, the inhalation module 104 and/or the
exhalation module 108 receive commands or instructions for
executing a breath type from a VC+ module 117, a BL module 118, or
a VCI module 119. In some embodiments, the controller 110 receives
commands or instructions for executing a breath type from the VC+
module 117, the BL module 118, or the VCI module 119. In other
embodiments, the pneumatic system 102 receives commands or
instructions for executing a breath type from the VC+ module 117,
the BL module 118, or the VCI module 119. In further embodiments,
not shown, the VC+ module 117, the BL module 118, or the VCI module
119 are located separate from the controller 110, within the
pneumatic system 102, or separate from the controller 110 and the
pneumatic system 102.
[0053] The VC+ module 117 provides instructions or commands for
executing a volume-targeted pressure-controlled breath type as
described above. The BL module 118 provides instructions or
commands for operating the ventilator in the BiLevel.TM. mode while
delivering any of the various breath type as described above. The
VCI module 119 provides instructions or commands for executing a
volume-targeted airway pressure release ventilation with a
guaranteed minimal pressure or a volume-targeted minimum
pressure-controlled breath type. The purpose of the VCI breath type
is to utilize the benefits of VC+ and BL while reducing the
disadvantages of these breath types during the ventilation of
patients, such as weak patients with H1N1 and ARDS patients.
[0054] The VCI module 119 provides instructions for the delivery of
a VCI breath type based on a received tidal volume. One of the
major hurdles to the use of BL is clinician unfamiliarity. Because
clinicians are unfamiliar with setting PEEP.sub.H and PEEP.sub.L,
many choose to use familiar volume control breath types instead of
learning a new, different breath type. Most clinicians are familiar
with setting a tidal volume making the use of a VCI breath type an
easier transition. Further, the received limitation on tidal volume
helps to prevent patients from receiving more than a desired tidal
volume of gas. The VCI module 119 provides similar instruction to
the inhalation and exhalation module as the VC+ module 117 except
the VCI module 119 provides instructions for a minimum inspiration
pressure (P.sub.MIN) and allows a VCI breath type with an inverse
I:E ratio of greater than 4:1.
[0055] The VCI module 119 provides instructions that require the
VCI breath type to maintain a P.sub.MIN, unlike the VC+ module 117
that allows P.sub.i to fall to zero. The VCI module 119 compares
the calculated P.sub.i to the P.sub.MIN. If the calculated P.sub.i
is less than the P.sub.MIN, the VCI module 119 provides
instructions to deliver the P.sub.MIN in the next or following
inspiration. If the calculated P.sub.i is at least the P.sub.MIN,
then the VCI module 119 provides instructions to deliver the
calculated P.sub.i in the next or following inspiration. In some
embodiments, the P.sub.MIN is input or selected by the operator. In
other embodiments, the P.sub.MIN is determined by the ventilator
based on or derived from other ventilator parameters, patient
parameters, and/or operator input. In some embodiments, the
ventilator utilizes a stored default value for P.sub.MIN if the
operator does not select or input a P.sub.MIN.
[0056] In some embodiments, the VCI module 119 provides
instructions that require the VCI breath type to maintain a
pressure maximum (P.sub.MAX), unlike the VC+ module 117 that allows
P, to rise to any calculated level based on the amount of tidal
volume pulled in the previous breath. The VCI module 119 compares
the calculated P.sub.i to the P.sub.MAX. If the calculated P.sub.i
is more than the P.sub.MAX, the VCI module 119 provides
instructions to deliver the P.sub.MAX in the next or following
inspiration. If the calculated P.sub.i is at least the P.sub.MAX,
then the VCI module 119 provides instructions to deliver the
calculated P.sub.i in the next or following inspiration. In some
embodiments, the P.sub.MAX is input or selected by the operator. In
other embodiments, the P.sub.MAX is determined by the ventilator
based on or derived from other ventilator parameters, patient
parameters, and/or operator input, such as P.sub.MIN. In some
embodiments, the ventilator utilizes a stored default value for
P.sub.MAX if the operator does not select or input a P.sub.MAX.
[0057] The VCI module 119 determines the respiration rate and I:E
ratio by receiving at least two of an inspiration time, an
exhalation time, an I:E ratio, and a respiratory rate. Depending
upon the received parameters, the VCI module 119 will send
instructions for an inverse I:E ratio of greater than 4:1 as would
be allowed by the BL module 118 and unlike the VC+ module 117 that
will only provide instructions for an LE ratio of 4:1 or less. This
inverse ratio is particularly beneficial to ARDS patients and other
weak patients, such as H1N1 patients.
[0058] In some embodiments, the VCI module 119 further receives a
fractional inspired oxygen setting (FiO.sub.2) for controlling the
VCI breath type. In some embodiments, the VCI module 119 further
receives a PEEP for controlling the VCI breath type. In other
embodiments, the VCI module 119 further receives a rise time for
controlling the VCI breath type. As discussed above, the, VCI
module 119 may further receive a P.sub.MIN and/or a P.sub.MAX for
controlling the VCI breath type.
[0059] Further, the VCI module 119 detects patient initiated
triggers above the given P.sub.i and PEEP during inspiration and
exhalation based on received sensor data and information similar to
the BL module 118, which allows and tracks patient triggered
spontaneous inspirations above the given PEEP.sub.H and PEEP.sub.L.
The VCI module 119 sends instructions allowing the patient to pull
additional volume above what is provided at P.sub.i and PEEP based
on detected patient initiated triggers. While the VCI module 119
tracks each patient initiated trigger, including, number, duration,
volume, pressure, etc., the VCI module 119 does not utilize this
information in the calculation of the next P.sub.i. VCI module 119
calculates the P.sub.i for the next inhalation based solely on the
amount of tidal volume taken by the patient during the delivery of
the previous P.sub.i for the initiation of inhalation. In one
embodiment, the tidal volume is calculated based on an output
indicative of an inspiration flow from a sensor 107.
[0060] Additionally, the VCI module 119 may provide instructions
for providing pressure support to any detected patient initiated
breath above the delivered PEEP and P.sub.i based on a received
pressure support (P.sub.SUPP) setting, which is similar to the BL
module 118 that provides instructions for supporting detected
patient initiated inspirations above the set PEEP.sub.H and
PEEP.sub.L based on a received P.sub.SUPP setting. The
P.sub.SUPPsetting may be any parameter for providing additional
pressure as known by a person of skill in the art for ventilating a
patient. For example, the P.sub.SUPP may vary based on the amount
of volume pulled by the patient or may be a set amount or percent
of pressure that is given regardless of the amount of volume pulled
by the patient.
[0061] Any suitable type of triggering detection for determining a
patient trigger may be utilized by the ventilation system, such as
nasal detection, diaphragm detection, and/or brain signal
detection. Further, patient triggering may be detected via a
pressure-monitoring method, a flow-monitoring method, direct or
indirect measurement of neuromuscular signals, or any other
suitable method. Sensors suitable for this detection may include
any suitable sensing device as known by a person of skill in the
art for a ventilator.
[0062] As used herein, any parameters received by the VCI module
119 are input by the clinician, selected by the clinician, or
provided by the ventilator. The ventilator may derive the received
parameter based on patient parameters, ventilator parameters,
and/or input or selected clinician data. In some embodiments, the
ventilator contains stored default values, which the ventilator
utilizes as the received parameter when the clinician does not
input or select a parameter.
[0063] FIG. 2 illustrates an embodiment of a method 200 for
ventilating a patient on a ventilator with a VCI breath type. As
illustrated, method 200 includes a receive operation 202. During
the receive operation 202, the ventilator determines or receives a
tidal volume, a PEEP, a P.sub.MIN, and at least two of a
respiration rate, an inhalation time, an expiration time, or an I:E
ratio, such as via direct selections of a value for each parameter
made by a clinician. The received parameters may be saved default
settings stored within the ventilator, input by a clinician, chosen
by a clinician, and/or derived by the ventilator based on other
patient parameters, ventilator parameters, or inputted parameters.
In some embodiments, during the receive operation 202, the
ventilator further determines or receives FiO.sub.2, rise time,
P.sub.SUPP, and/or P.sub.MAX.
[0064] In some embodiments, the operator inputs or selects the
received tidal volume and/or PEEP for the VCI breath type during
receive operation 202. One of the major hurdles to the use of BL is
clinician unfamiliarity. Because clinicians are unfamiliar with
setting PEEP.sub.H and PEEP.sub.L, many chose to use familiar
volume control breath types instead of learning a new, different
breath type. Most clinicians are familiar with setting a tidal
volume making the use of a VCI breath type an easier transition.
Further, the received tidal volume helps to prevent patients from
receiving more than a desired tidal volume of gas.
[0065] In some embodiments, when the operator does not input a
tidal volume and/or PEEP.sub.i the ventilator receives the tidal
volume and/or PEEP from a stored default value during receive
operation 202. In further embodiments, the ventilator derives the
stored default values based on other ventilator or patient
parameters. The ventilator performs the receive operation 202
anytime the ventilator receives a new tidal volume, a new PEEP, a
new P.sub.MIN, and at least two of a new respiration rate, a new
inhalation time, a new expiration time, or a new I:E ratio, such as
via direct selections by a clinician.
[0066] Further, the ventilator during receive operation 202
determines the respiration rate and the I:E ratio by receiving at
least two of an inspiration time, an exhalation time, an I:E ratio,
and a respiratory rate. Unlike a VC+ breath type, the ventilator in
the receive operation 202 will accept parameters that lead to an
inverse I:E ratio of greater than 4:1. VC+ breath types only allow
for an I:E ratio of 4:1 or less. The inverse I:E ratio of greater
than 4:1 is, however, often utilized during BL breath types. This
inverse ratio is particularly beneficial for ARDS patients and
other weak patients, such as H1N1 patients.
[0067] As discussed above, the VCI breath type utilizes
measurements from the previous breath to determine an inspiration
pressure to delivery in a next breath. Accordingly, if no data has
been collected by the ventilator, the ventilator during method 200
cannot calculate an inspiration pressure for delivery in the next
breath. In one embodiment, this is addressed by calculating or
selecting a default inspiration pressure to be used for the initial
breath. The ventilator during method 200 delivers a test breath at
the beginning of the VCI breath type when no data has been
collected. The test breath is a VC breath that delivers the initial
pressure. In some embodiments, the default pressure is derived from
the received tidal volume. Alternatively, the default pressure may
be determined from the patient's ideal body weight, previous
treatment pressures, or any other factor.
[0068] Further, method 200 includes a calculate operation 204. The
calculate operation 204 is performed by the ventilator at the
beginning of each breath. During the calculate operation 204, the
ventilator calculates an inspiration pressure based on measurements
taken from the previously delivered inspiration including the test
breath. In an embodiment, the ventilator during calculate operation
204 measures the inhaled volume and the inspiratory pressure at the
beginning of each breath in order to estimate the patient's
compliance. For example, at the beginning of each breath, the
ventilator retrieves data regarding the end-inspiratory pressure
(EIP), the end-expiratory pressure (EEP), and the delivered volume
associated with the last breath cycle. Delivered volume is
determined based on integrating the net flow during the last
inspiration and applying various volume compensations (e.g., tube
compliance). Next, for example, the ventilator may utilize the
retrieved data, the received tidal volume, and the patient's ideal
body weight (IBW) and/or other monitored data to estimate patient
compliance and calculates a revised effective pressure for use in
the next breathing cycle that is projected to deliver the received
tidal volume. The patient's compliance is put into an algorithm to
calculate the amount of inspiratory pressure necessary for the next
breath in order to deliver the received tidal volume. Alternative
embodiments of how the calculate operation 204 calculates the
inspiratory pressure to be delivered are also possible and any
suitable method may be used. As another example, the percentage
difference between the delivered and set tidal volumes may be
calculated and the previously delivered pressure may be adjusted
based on that difference.
[0069] The measurements allow the ventilator to determine the
amount of tidal volume pulled by the patient at the beginning of
the previous breath. If amount of tidal volume pulled by the
patient is more than the received tidal volume, the ventilator
calculates a lower inspiration pressure. If amount of tidal volume
pulled by the patient is less than the received tidal volume, the
ventilator calculates a higher inspiration pressure. Accordingly,
the VCI breath type provides the patient with the received tidal
volume by adjusting the provided pressure support in the next or
following breath. Based on the amount of tidal volume pulled by the
patient at the previous pressure, the ventilator in the calculate
operation 204 determines the necessary amount of inspiration
pressure (P.sub.i) to achieve the received tidal volume during the
next inspiration by the patient.
[0070] Method 200 includes a compare operation 206. The ventilator
during compare operation 206 compares the calculated P.sub.i to a
received minimum pressure (P.sub.MIN). The P.sub.MIN setting is the
minimum amount of pressure the ventilator must provide during
inspiration. The received P.sub.MIN may be operator selected,
input, or determined by the ventilator. In some embodiments, the
ventilator may derive the P.sub.MIN based on other ventilator or
patient parameters, or may have a stored default value for
P.sub.MIN when P.sub.MIN is not selected or input by the operator.
In some embodiments, the ventilator during compare operation 206
further compares the calculated P.sub.i to a received maximum
pressure (P.sub.MAX). The P.sub.MAX setting is the maximum amount
of pressure the ventilator is allowed to provide during
inspiration. The received P.sub.MAX may be operator selected,
input, a default value, a value determined from some other
parameter such as the patient's age, sex, body weight, ideal body
weight, lung compliance, etc. or as otherwise determined by the
ventilator. In some embodiments, the ventilator may derive the
P.sub.MAX based on other parameters, such as P.sub.MIN, or may have
a stored default value for P.sub.MAX when P.sub.MAX is not selected
or input by the operator.
[0071] Next, method 200 includes a minimum determination operation
208. The ventilator during the minimum determination operation 208
determines if the calculated P.sub.i is greater than the P.sub.MIN.
If the ventilator determines during the minimum determination
operation 208 that the calculated P.sub.i is less than the
P.sub.MIN, then the ventilator performs a P.sub.MIN delivery
operation 210. If the ventilator determines during the minimum
determination operation 208 that the calculated P.sub.i is at least
the P.sub.MIN, then the ventilator performs the P.sub.i delivery
operation 214.
[0072] In some embodiments, if the ventilator determines during the
minimum determination operation 208 that the calculated P.sub.i is
at least the K.sub.IN, then the ventilator performs a P.sub.MAX
determination operation 212 instead of the P.sub.i delivery
operation 214. During the P.sub.MAX determination operation 212,
the ventilator determines if the calculated P.sub.i is greater than
the P.sub.MAX. If the ventilator determines during the maximum
determination operation 212 that the calculated P.sub.i is at least
the P.sub.MAX, then the ventilator performs a P.sub.MAX delivery
operation 216. If the ventilator determines during the maximum
determination operation 212 that the calculated P.sub.i is less
than the P.sub.MAX, then the ventilator performs the P.sub.i
delivery operation 214.
[0073] As discussed above, method 200 includes the P.sub.MIN
delivery operation 210. The ventilator during the P.sub.MIN
delivery operation 210 delivers an inspiration pressure at the
received P.sub.MIN setting. For example, if P.sub.MIN was set to 25
cm H.sub.2O, the ventilator in the P.sub.MIN delivery operation 210
would deliver an inspiration pressure of 25 cm H.sub.2O. The
P.sub.MIN setting may be set automatically by the ventilator based
on ventilator or patient parameters, may be a stored default value,
or may be input or selected by the operator. The received P.sub.MIN
prevents the P.sub.i from falling to a minimum of 5, which may
happen in a VC+ breath type. This minimum pressure is beneficial in
weak patients that need a minimum level of pressure support to
promote adequate gas exchange in the lungs and support a reasonable
amount of work for the patient in the acute lung injury state.
After the performance of the P.sub.MIN delivery operation 210, the
ventilator performs exhalation operation 218.
[0074] Method 200 further includes the P.sub.i delivery operation
214. The ventilator during the P.sub.i delivery operation 214
delivers the calculated P.sub.i determined by the ventilator in the
calculate operation 204. For example, if the ventilator in the
calculate operation 204 calculates a P.sub.i of 28 cm H.sub.2O, the
ventilator during the P.sub.i delivery operation 214 delivers 28 cm
H.sub.2O of inspiration pressure. After the performance of the
P.sub.MIN delivery operation 210, the ventilator performs
exhalation operation 218.
[0075] In some embodiments, method 200 further includes the
P.sub.MAX delivery operation 216. The ventilator during the
P.sub.MAX delivery operation 216 delivers an inspiration pressure
at the received P.sub.MAX setting. For example, if P.sub.MAX was
set to 35 cm H.sub.2O, the ventilator in the P.sub.MAX delivery
operation 210 would deliver an inspiration pressure of 35 cm
H.sub.2O. The P.sub.MAX setting may be set automatically by the
ventilator based on ventilator or patient parameters, may be stored
default valued, or may be input or selected by the operator. The
received P.sub.MAX prevents the P.sub.i from increasing to a level
that could cause damage to the lungs, such as barotrauma. After the
performance of the P.sub.MIN delivery operation 210, the ventilator
performs exhalation operation 218.
[0076] As discussed above, method 200 includes an exhalation
operation 218. The ventilator during the exhalation operation 218,
triggers and executes an exhalation by the patient. The transition
between inspiration to exhalation may be synchronized to a
patient's spontaneous breathing efforts and/or to the
ventilator-controlled breaths. For example, when the set inhalation
time is reached the ventilator initiates exhalation regardless of
actual tidal volume delivered in that breath. Exhalation lasts from
the end of inspiration until the beginning of the next inspiration.
For instance, in a non-triggering patient, the exhalation time
(T.sub.E) is based on at least two of a received respiration rate,
a received inhalation time, a received expiration time, or a
received I:E ratio.
[0077] Upon the end of exhalation, another mandatory breath is
given to the patient. At the end of exhalation or at the beginning
of the next mandatory breath the ventilator repeats at least a
portion of method 200. As illustrated in FIG. 2, the ventilator
performs calculate operation 204 at the beginning of the next
mandatory breath followed by the following steps of method 200.
Alternatively, if the ventilator received new parameters, such as a
new tidal volume, the ventilator performs receive operation 202 at
the beginning of the next mandatory breath followed by the
following steps of method 200. Accordingly, at least a portion of
method 200 is performed for each mandatory breath given by the
ventilator during method 200.
[0078] In some embodiments, the ventilator during method 200 may
detect patient initiated triggers above the given P.sub.i and PEEP
during inspiration and exhalation based on received sensor data and
information similar to the BL breath type, which allows and tracks
patient triggered spontaneous inspirations above the given
PEEP.sub.H and PEEP.sub.L. In these embodiments, the ventilator
allows the patient to pull additional volume above what is provided
at P.sub.i and PEEP based on detected patient initiated triggers.
In further embodiments, the ventilator during method 200 may track
each patient initiated trigger, including, number, duration,
volume, pressure, etc. However, the ventilator during method 200
does not utilize this information in the calculation of the next
P.sub.i during calculation operation 204. Accordingly, during these
embodiments, the ventilator during method 200 calculates the
P.sub.i for the next inhalation based solely on the amount of tidal
volume taken by the patient during the delivery of the previous
P.sub.i for the initiation of inhalation during calculation
operation 204.
[0079] In further embodiments, the ventilator during method 200
provides pressure support to any detected patient initiated breaths
above the delivered PEEP and P.sub.i based on a received pressure
support (P.sub.SUPP) setting. The P.sub.SUPP setting may be any
parameter for providing additional pressure as known by a person of
skill in the art for ventilating a patient. For example, the
P.sub.SUPP may vary based on the amount of volume pulled by the
patient or may be a set amount or percent of pressure that is given
regardless of the amount of volume pulled by the patient. In some
embodiments, P.sub.SUPP is limited by P.sub.MAX. In these
embodiments, the P.sub.SUPP will not provide a pressure that is
greater than P.sub.MAX. In some embodiments, P.sub.SUPP is not
limited by P.sub.MAX. In these embodiments, the P.sub.SUPP provided
may exceed a received P.sub.MAX.
[0080] Any suitable type of triggering detection for determining a
patient trigger may be utilized by the ventilation system, such as
nasal detection, diaphragm detection, and/or brain signal
detection. Further, patient triggering may be detected via a
pressure-monitoring method, a flow-monitoring method, direct or
indirect measurement of neuromuscular signals, or any other
suitable method. Sensors suitable for this detection may include
any suitable sensing device as known by a person of skill in the
art for a ventilator.
[0081] In some embodiments, the ventilator during method 200
executes an alarm when the received tidal volume is not delivered
to the patient. In some embodiments, the ventilator during method
200 executes an alarm when the inspired volume of the patient is
above a predetermined threshold. These parameters are also tracked
and alarm if above predetermined thresholds during a VC+ breath
type. The term "alarm" as used herein includes any suitable visual,
audio, and/or vibrational notification. Further, the term "alarm"
as used herein further includes sent messages, such as emails, SMS
text messages, and/or other transmitted notifications.
[0082] In one embodiment, the steps of method 200 are performed by
a computer-readable medium having computer-executable instructions.
In another embodiment, the ventilator system includes means for
performing the steps of method 200. The means for performing the
steps of method 200 are disclosed above, such as in ventilator
100.
[0083] In another embodiment, the ventilator system includes means
for receiving a tidal volume and a PEEP; means for receiving a
minimum inspiration pressure; means for receiving at least two of
an inspiration time, an exhalation time, an I:E ratio, and a
respiratory rate; means for calculating a calculated pressure based
on measurements taken from a previous inspiration indicative of
tidal volume delivered to the patient; means for comparing the
calculated pressure to the received minimum inspiration pressure;
means for delivering a delivered inspiration pressure during a next
inhalation to the patient, the delivered inspiration pressure
determined based on the step of comparing the calculated pressure
to the received minimum inspiration pressure; and means for
delivering, after the next inhalation, the received PEEP
Example 1
[0084] FIG. 3 illustrates an embodiment of a pressure waveform
showing changes from inspiration to exhalation during a VCI breath
type. During inspiration, the pressure waveform illustrates the
amount of pressure delivered during the initial inspiration based
on solid line segment. Exhalation to the received PEEP is shown by
a dotted line segment in FIG. 3. During inspiration and exhalation
any additional pressure support provided in response to a detected
spontaneous breath is designated by a dashed line segment.
[0085] Those skilled in the art will recognize that the methods and
systems of the present disclosure may be implemented in many
manners and as such are not to be limited by the foregoing
exemplary embodiments and examples. In other words, functional
elements being performed by a single or multiple components, in
various combinations of hardware and software or firmware, and
individual functions, can be distributed among software
applications at either the client or server level or both. In this
regard, any number of the features of the different embodiments
described herein may be combined into single or multiple
embodiments, and alternate embodiments having fewer than or more
than all of the features herein described are possible.
Functionality may also be, in whole or in part, distributed among
multiple components, in manners now known or to become known. Thus,
myriad software/hardware/firmware combinations are possible in
achieving the functions, features, interfaces and preferences
described herein. Moreover, the scope of the present disclosure
covers conventionally known manners for carrying out the described
features and functions and interfaces, and those variations and
modifications that may be made to the hardware or software firmware
components described herein as would be understood by those skilled
in the art now and hereafter.
[0086] Numerous other changes may be made which will readily
suggest themselves to those skilled in the art and which are
encompassed in the spirit of the disclosure and as defined in the
appended claims. While various embodiments have been described for
purposes of this disclosure, various changes and modifications may
be made which are well within the scope of the present invention.
Numerous other changes may be made which will readily suggest
themselves to those skilled in the art and which are encompassed in
the spirit of the disclosure and as defined in the appended
claims.
* * * * *